1. Field of the Invention
This invention relates to semiconductor devices, and more particularly, to gallium nitride/aluminum gallium nitride/gallium nitride (GaN/AlGaN/GaN) dispersion-free high electron mobility transistors (HEMTs).
2. Description of the Related Art
GaN power HEMTs suffer from “DC-to-RF dispersion,” which is defined as the difference between the static and dynamic (e.g. gate lag measurement) I-V characteristics. This dispersion has been reported to be due to the slow response of the surface traps. In the prior art, silicon nitride (SiN) passivation has been used to suppress this problem, but the drawback of SiN passivation is that it is very sensitive to both surface and deposition conditions, which leads to poor reproducibility.
What is needed, then, are improved methods of fabricating dispersion-free GaN-based HEMTs without SiN passivation.